Heavy metal(loid) hazards in groundwater near the Menzel Bourguiba (Tunisia) smelting site

Smelting and mining operations have a far-reaching impact on groundwater quality as they are the primary anthropogenic source of heavy metal(loid)s (HMs). This study investigated the HM contamination of groundwater in the Menzel Bourguiba aquifer near a steel smelter in Tunisia. Twenty-eight groundwater samples were collected and analyzed for nine HMs (Cd, As, Cu, Fe, Mn, Cr, Ni, Zn, and Pb). Contamination factor (CF), pollution load index (PLI), and entropy-weighted water quality index (EWQI) were used to assess pollution levels. The human health risks to adults and children posed by HMs through ingestion and dermal exposure were evaluated using both deterministic and Monte Carlo approaches. Results showed that Fe had the highest average concentration (420 µg/L), followed by Zn, Cu, Mn, Cr, Pb, Ni, As, and Cd. Based on CF values, groundwater was uncontaminated concerning Cu, Mn, and Zn, while contamination levels of the remaining HMs varied significantly across samples. Correspondingly, PLI values indicated that most groundwater samples were unpolluted, except for those near the smelter site. EWQI indicated good to excellent water quality. Both children and adults face considerable non-carcinogenic health risks. Monte Carlo simulations estimated the average incremental lifetime cancer risk (ILCR) at 5.26 × 10–4 for adults and 1.72 × 10–4 for children, both exceeding the acceptable threshold (ILCR > 10–4), indicating significant carcinogenic risks. This study highlights the need for an integrated approach to accurately assess groundwater pollution and health risks, particularly in Tunisia’s mining and smelter areas.